System and method for monitoring transient stability in a hybrid loadflow computer arrangement with transient stability analysis capability

ABSTRACT

A hybrid loadflow computer arrangement includes an analog network simulator and a digital computer which interchange signals through analog input and output circuitry during transient analysis. The analog simulator includes modular bus, generator, load, tie line and line DC circuits representative of electric power system buses, generators, loads, tie lines and lines. The analog simulator provides generator swing angles and generator rotational velocities to the digital computer. The computer monitors the generator swing angles and rotational velocities to determine and indicate whether they are within predetermined tolerances.

United States Patent n91 Carlson et al.

SYSTEM AND METHOD FOR MONITORING TRANSIENT STABILITY IN A HYBRID LOADFLOW COMPUTER ARRANGEMENT WITH TRANSIENT STABILITY ANALYSIS CAPABILITY Assignee:

Filed:

Appl. No.: 254,859

Inventors: Norman R. Carlson, Export; Paul H.

Haley, Pittsburgh, both of Pa.; Mark K. Enns, Ann Arbor, Mich.

Westinghouse Electric Corporation, Pittsburgh, Pa.

May 19, 1972 US. Cl 444/1, 235/l51.21, 307/18 Int. G 06j l/00, G06f 15/06, G06f 15/56 Field of Search 235/15l.2l, 150.5; 307/18,

System Operations; G. W. Stagg, J. F. Dopazo, O. A. Klitin, & L. S. Vanslyck; IEEE Transactions on Power Apparatus and Systems; Vol. PAS-89, No. 4, April Load Flows Using a Combination of Point Jacobi and Newtons Methods; Y. P. Dusonchet, S. N. Talukdar, H. E. Sinnot; IEEE Transactions on Power Apparatus and Systems; Vol. PAS-90, No. 3, May/June 1971, pp 941-949.

Computer Control of Power Systems; The Engineer, Oct. 2, 1964.

Primary ExaminerCharles E. Atkinson Assistant Examiner-Edward .1. Wise Attorney, Agent, or Firm- E. F. Possessky 57 ABSTRACT A hybrid loadflow computer arrangement includes an analog network simulator and a digital computer References Cited UNITED STATES PATENTS 9/1967" Kaufman et a1. 235/150.5 X 6/1971 Brussolo 235/150.5 v 7/1972 Mitsui et al 235/184 X 10/1972 Van Essen 340/1725 X 10/1972 Cohn 235/184 X OTHER PUBLICATIONS Load Flows by Hybrid Computation for Power System Operations; M. Enns, T. C..Giras, & N. R. Carlson; IEEE Transactions on' Power Apparatus and Systems, Nov./Dec. 1971, pp. 2540-2547.

which interchange signals through analog input and output circuitry during transient analysis. The analog simulator includes modular bus, generator, load, tie line and line DC circuits representative of electric power system buses, generators, loads, tie lines and lines. The analog simulator provides generator swing angles and. generator rotational velocities to the digital computer. The computerv monitors the generator swing angles and rotational velocities to determine and indicate whether they are within predetermined tolerances.

4 Claims, 41 Drawing Figures LOAD NORTH r' 7 l3 EHV(5OOKV 3m 4 5 G25 0 AD 7 g 3 PHILADELPHIA {20' 2| A 56 3 47 EHV l4 l i /38 BUFFALO I 26 nmo 'WASHINGTON WHEELING I9 WEST PAIENIEDSEP 3 m 3.883.927

MU D1 of 23 v NORTH r? I3 I L EHV(5OOKV 3a) 4 5 25 I LOAD f 3 34 PHILADELPHIA 2 3 47 EHV I H I I4 c BUFFALO 2 e -LoAI EHV WASHINGTON /96 23 WHEELING I WEST LOAD F|G.l

INJECTION CURRENT vALvEs 4| D/A 4O TRANSMISSION LINE OUTAGE SWITCHING NETWORK A SIMULATOR /D LOAD.TiES. BUS VOLTAGE VALVES LINESBUSES GENERATION TRANSFORMERS FIG/2 PAIENTEDSEP 3 w 1 3833927 sum 03 or 23 p FIG? PATENTEDSEP 31974 I 3.883.927 SHEET "05 0F 23 LINE ou'TAGE SWITCHING A/D BUS voLTAGE'AND LINE CURRENT SOLUTIONS 4'0 4I3 4l2- 4II I D/A ANALOG [E] ANALoG [E] DIGITAL POWER DYNAMIC BUS ANALoG COMPUTER VOLTAGE GENERATOR LINE LOADS SET POINTS MODULES Us] MODULES [IT] SWING ANGLES [E] RoTATIoNAL vELoITIEs ,4I4 D/A INFINITE BUS VOLTAGE 'g kfig sET POINTS INFINITE I BUSES DCU'S FORLOADADMITTANCE ADJUSTMENTS FIG. IO LINE cuRRENT AND 4'3 l BUS VOLTAGE sDLuTIoNsj [4" WA [1 BUS [E] DIGITAL COMPUTER LINE OUTAGE- -685 'gZ Q SWITCHING MO 5 [IL] ANlLgCg TIE A INFINITE BUSES FIG II DCU'S LOAD ADMITTANCE ADJUSTMENT FAuLTING DEvIcE I 2 FAuLTING 344 0 s DEVICE 304 336 333 I {K/i W K6 K EM 7 FIG.I2

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sum oaur23 Q REAL BUS F|G.I5A. VOLT INPUT M F? IMAGINARY Rue BUS VOLT INPUT sum 1 or 23 ALI ALZ

ALB

III

PAIENIEMU 3W4 3.8%8-927 sum :12 or 2 INTRONICS MULTIPLIER INTRONICS MULTIPLIER PAIENIEB SEP 3191.4

sum 13 or 2 )70 f 705 A? Q SIGNAL w I CLOCK 100x GENERATOR r- ;:/7|4

*0 mm 70o 7 6 O 707.

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T J25 LINE Pr I Rd a

GENERATOR-M BUS 5|2 OS 72? TD LOAD BUS FIG. 20

PAIENI08P awn 3,833,927 sum '1: or 23 SIOl-SIO5 |20| T |2|OI |2ll v r v J-- I THE-T iTLTiTLT I g b T MTTI IT T IT T T T T TT-T TYPICAL TYPICAL. v 202/ GENERATOR LOAD MODULE MODULE FIG. 22A FIG. 228.

221 ICCOPIZZT I226 12 50 |23| I203 I206 I207 I208 l209 I210 V I E I222 VATR] [Vii] Loco cco E/ j 1205 (VAR r I I V BUS GENERATOR LOAD LINE TIE LINE MODULE MODULE MODULE MODULE MODULE FIG. 27

D/A IEI. PM GENERATOR sET POINTS MODELS s] DATA h-Q TRANSFORMER [Ifl 983LINK A/D ANAt-OG NET TIE LINE I sI MU LATOR MODELS SOLUTION [E] 982 I ,[IL]

- LOAD AOMITT. LOAD SETTINGS MODELS SYSTEM STUDY OPERATORS MODE AIIIIIIEIIsIP sIIII mama? sum I'HIF '23 0/11 INF. BUS VOLTAGES 

1. A hybrid loadflow computer arrangement having transient stability analysis capability comprising a DC analog simulator of an AC network, said simulator including a plurality of bus, generator, load, tie line and line DC circuits interconnected to correspond to the AC network, a digital computer, analog input and output systems for transferring signals between said computer and said simulator, said signals including generator swing angle and rotational velocity signals transferred to said digital computer, said digital computer including means for monitoring said generator swing angle and rotational velocity signals for each generator, and said digital computer including means for indicating whether said generator swing angle signals and rotational velocity signals are within predetermined tolerances.
 2. A method for transient monitoring of a hybrid loadflow computer arrangement with transient staBility analysis capability comprising the steps of using a DC analog simulator of an AC network to calculate predetermined network parameters including network generator swing angles and rotational velocities, using a digital computer to monitor said generator swing angles and rotational velocities and to indicate whether said generator swing angles and rotational velocities are within predetermined tolerances.
 3. A hybrid loadflow computer arrangement having transient stability analysis capability comprising a DC analog simulator of an AC network, said simulator including a plurality of bus, generator, load, tie line and line DC circuits interconnected to correspond to the AC network, a digital computer, analog input and output systems for transferring signals between said digital computer and said analog network simulator, said signals including generator swing angle and generator rotational velocity signals transferred to said digital computer, said digital computer including means for performing a transient monitoring scanning operation for a predetermined number of scans, said digital computer including means for determining a first sum of stored rotational inertia values for each system generator and a second sum of the products of each of said rotational inertia values and corresponding generator swing angle values, said digital computer including means for determining an average swing angle as a function of said first and second sums for each scan, said digital computer including means for determining whether the differences between said average swing angle value and each generator swing angle value are within a predetermined tolerance, and whether each of the generator rotational velocities are within a predetermined tolerance for each scan, and said digital computer including means for indicating whether said tolerances have been met for each system generator during each scan.
 4. A method for transient monitoring of a hybrid loadflow computer arrangement with transient stability analysis comprising the steps of using a DC analog simulator of an AC network to calculate predetermined network parameters including network generator swing angles and rotational velocities, using a digital computer to perform a transient monitoring scanning operation for a predetermined number of scans with steps including the determination of a first sum of stored rotational inertia values for each network generator, the determination of a second sum of the products of each of said rotational inertia values and corresponding generator swing angle values, the determination of an average swing angle as a function of said first and second sums, the determination of whether the differences between said average swing angle and each generator swing angle value are within a predetermined tolerance, the determination of whether each of the generator rotational velocities are within a predetermined tolerance and the indication of whether said tolerances have been met for each network generator. 